Analyzing power measurements for the [Formula Presented] breakup reaction at 12 MeV

We report the most extensive set of vector [Formula Presented] and tensor [Formula Presented] and [Formula Presented] analyzing-power data for the [Formula Presented] reaction. Two-particle coincidence data have been measured for six deuteron-proton, three deuteron-neutron and three proton-neutron angle pairs at an incident deuteron energy of 12.0 MeV. These data are compared to impulse-approximation calculations that treat the underlying nucleon-deuteron system exactly and include contributions from both target and projectile breakup processes. This model gives a good description of the analyzing-power and relative cross-section data. We show that the inclusion of nucleon-nucleon [Formula Presented] interactions considerably improves the agreement with the spin observables. The disagreement between the data and theoretical predictions show the limitations in our model and the importance of the rescattering processes. We suggest that the [Formula Presented] three-body breakup process will provide useful information on the nucleon-nucleon force when exact calculations become available.